SEVENTY-TWO people were arrested at this year’s V Festival in Chelmsford.
Some 53 people were arrested for drug possession, seven for selling legal highs, three for theft and one for assault.
St John’s Ambulance treated 500 people over the weekend with ten taken to hospital.
More than 180,000 attended this year’s event.
Government scientists also attended, to analyse samples of "legal highs", including nitrous oxide, or laughing gas.
Three people at the event's sister site in Staffordshire, required urgent medical help on Saturday after taking blue tablets, known as Blue Ghost.
Chief Insp Jon Haytor from Essex Police said: "No one was arrested for using nitrous oxide, or laughing gas, but a number of arrests were made for supplying so-called legal highs.”
Festival organisers said nitrous oxide and "legal highs" were banned from the event, and any substances found were confiscated.
An Essex Trading Standards spokesman said 10 festival-goers, who were caught with nitrous oxide, were removed from the site.
Equipment, including balloons and gas canisters, was also seized.
Inhaling nitrous oxide is not illegal.
Essex Police said those selling the substance had been arrested on suspicion of administering prescription-only medicine, contrary to the Human Medicines Act 2012.